Add alloc instruction to Patio IR

4 files changed, 18 insertions, 4 deletions

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
index 790bf8d7..dfe1e04b 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
@@ -17,8 +17,8 @@ public class PatioCodeGen {
             case DiscardInstruction discard ->
                 P.vector(new PatioDiscard(discard.source()));
 
-            case ReturnInstruction discard ->
-                P.vector(new PatioReturn(discard.source()));
+            case ReturnInstruction return_ ->
+                P.vector(new PatioReturn(return_.source()));
 
             default ->
                 throw new IllegalStateException("Unexpected value: " + stackIrInstruction);
diff --git a/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java b/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
index 523eabc7..382c4125 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
@@ -1,5 +1,6 @@
 package org.shedlang.compiler.patio;
 
+import org.shedlang.compiler.patio.instructions.PatioAlloc;
 import org.shedlang.compiler.patio.instructions.PatioDiscard;
 import org.shedlang.compiler.patio.instructions.PatioInstruction;
 import org.shedlang.compiler.patio.instructions.PatioReturn;
@@ -33,10 +34,13 @@ public class PatioInstructionSerializer {
 
     private static Tree instructionToTree(PatioInstruction instruction) {
         return switch (instruction) {
+            case PatioAlloc alloc ->
+                treeList(treeIdentifier("alloc"), treeInt(alloc.bytes()));
+
             case PatioDiscard discard ->
                 treeList(treeIdentifier("discard"));
 
-            case PatioReturn patioReturn ->
+            case PatioReturn return_ ->
                 treeList(treeIdentifier("return"));
         };
     }
diff --git a/src/main/java/org/shedlang/compiler/patio/instructions/PatioAlloc.java b/src/main/java/org/shedlang/compiler/patio/instructions/PatioAlloc.java
new file mode 100644
index 00000000..c5ea9594
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/patio/instructions/PatioAlloc.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.patio.instructions;
+
+import org.shedlang.compiler.sources.Source;
+
+/**
+ * Allocate the given number of bytes, and push the pointer to the allocated
+ * memory onto the stack.
+ */
+public record PatioAlloc(int bytes, Source source) implements PatioInstruction {
+}
diff --git a/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java b/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
index 22305e84..6928d324 100644
--- a/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
+++ b/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
@@ -2,6 +2,6 @@ package org.shedlang.compiler.patio.instructions;
 
 import org.shedlang.compiler.sources.Source;
 
-public sealed interface PatioInstruction permits PatioDiscard, PatioReturn {
+public sealed interface PatioInstruction permits PatioAlloc, PatioDiscard, PatioReturn {
     Source source();
 }